What is High Blood Pressure and Low Blood Pressure?

I know that this is a common question for many people, so I want to address it. After reading this article, you’ll know what is high blood pressure, why it’s important to control it, and how to do so.

But firstly, you may be thinking:

Why bother with blood pressure?

People with diabetes are 2 – 3 times more likely to have heart disease than others. This is because diabetes can damage the blood vessels of many of our organs, causing them to be clogged up. Persistently high blood pressure has similar effects on our blood vessels. If someone has both diabetes and high blood pressure, the ill effects on the blood vessels are additive and hasten the progression of heart disease.

Although the main concern of someone with diabetes is managing their blood sugar levels – it is equally, if not more, important to keep blood pressure in check. This will significantly reduce the risk.

What does blood pressure really mean?

When you get a blood pressure reading (either at home or at your doctor’s), you actually get 2 numbers – for example, 130/80 or 150/90. Many people do not know what these two numbers represent, only ‘the lower, the better’.

To understand this better, here’s a crash course on how your heart works:

Your heart beats in two phases: contracting and relaxing.

During the contracting phase, the heart is pushing blood to your lungs and the rest of your body. The pressure inside the heart is higher during the contracting phase, because the heart muscle is actively squeezing. This is also known as ‘systole’ (pronounced ‘sis-toll-lee’) or ‘systolic’

In the relaxation phase, the heart muscle relaxes, and the heart fills up with blood from all parts of your body. The pressure inside the heart during relaxation is lower. This is known as ‘diastole’ (pronounced ‘die-as-toll-lee’) or ‘diastolic’

So your blood pressure is an indirect measure of the pressures in your heart during the two phases. The top number is your ‘systolic’ pressure, and the bottom number is your ‘diastolic’ pressure. Both numbers matter – so if your systolic pressure is normal but diastolic pressure is high, you are still at risk.

So, what is high blood pressure then?

There are several different stages of high blood pressure, but to summarise : if your blood pressure is 140/90 and above, consistently, you are likely to have high blood pressure.

A normal blood pressure is 120/80. This target number is based on many large scale clinical studies that show better health outcomes if blood pressure is kept below this range. Generally, the closer your number is to the normal value (120/80), the better your long term health. The blood pressure table below shows you the different ranges possible.

Source: American Heart Association

There is no clear definition of low blood pressure. If your blood pressure is less that 90/70 and you have symptoms like dizziness, lethargy, please see your doctor as soon as possible.

Measuring your blood pressure

Each time you visit your doctor or diabetes care nurse, you should ask them to check your blood pressure. It takes less than 2 minutes and is painless. Our blood pressure can fluctuate quite a bit depending on the time of the day, whether we were doing any physical activity earlier, our moods etc. Hence if you have a high reading, your doctor will often ask you to return several weeks later to re-check.

Nowadays, it is relatively cheap to have your own blood pressure monitoring device at home (<$100). All you need to do is wrap your arm in the cuff, and press the start button. The machine will automatically inflate and deflate the cuff and output a reading of your blood pressure.

Today, blood pressure monitors are very precise! Here are some tips to ensure an accurate reading:

Sit in a comfortable position.

Place your arm at the level of your chest (heart) when taking a measurement.

Rest for at least 5 minutes before taking a reading, if you were active/walking.

Getting your high blood pressure down

So now that you know what blood pressure is all about, how do I keep it within normal range, you ask?

The good news is that developing a healthy lifestyle not only positive impacts your blood pressure, but can also keep your blood glucose and cholesterol levels in control. Talk about killing 3 birds with one stone!

Healthy Eating

Exercising regularly

Reducing weight

1. Healthy Eating

Reducing the amount of salt in your diet is one of the most important steps you can do to keep your blood pressure in control. A specific kind of diet, called the DASH (Dietary Approaches to Stop Hypertension) diet, has been scientifically proven to lower blood pressure. This diet involves eating more fruits and vegetables, reducing the amount of food which are high in saturated or trans fat, and eating more whole-grain foods, fish, poultry and nuts.

You can find out more about the DASH diet here. (It’s ranked #1 in ‘Best diets overall’).

2. Exercising Regularly

Studies have shown that being more physically active can lower your systolic blood pressure by an average of 4 – 9 mmHg. That’s a big deal, and just as effective as some blood pressure medications. One caveat – You do have to keep exercising regularly in order to benefit for the long-term, so start making it a habit!

3. Reducing Weight

If you’re overweight (or just ‘horizontally challenged’), even a small weight loss can reduce your blood pressure and/or prevent high blood pressure in the future. Losing weight reduces the strain on your heart, allowing it to pump more effectively.

Your doctor may recommend that you start taking medications if your blood pressure is persistently high. There are many different types of medications for treating high blood pressure, and most of them are relatively safe with minimal side effects. The most important thing is to remember to take your medications regularly – otherwise they won’t work well!

If you’re wondering how you can begin a healthy lifestyle, the dietitians on GlycoLeap can teach you more about the DASH diet, and help you develop healthy habits for life. Find out more here.

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Yau Teng Yan

Dr Yau Teng Yan is a medical doctor with 8 years of professional experience in Singapore. He trained in Diagnostic Radiology, and has worked in clinical departments in various hospitals, including Emergency Medicine, Surgical ICU & Anaesthesiology.
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